Controls and indicators for a secondary operational mode of a computer system

ABSTRACT

A portable computer case whether in a closed state or open state permits a user to exercise control and monitor certain operating features. The user may toggle a control switch to place the computer system in a secondary operational mode, determine when a computer system is in a secondary operational mode, and adjust a digital master volume control during the secondary operational mode. The portable computer system includes a status indicator for indicating when a computer is in a secondary operational mode, digital master volume control buttons operable in a secondary operational mode, and a control switch for placing the computer system in a secondary operational mode. The status indicator, volume control buttons, and control switch are preferably provided on a top surface of the bottom shell of the portable computer for convenient access by a user. As such, a user is capable of placing the computer system in a secondary operational mode and determining when the computer system is in a secondary operational mode without opening the portable computer case. A user is also capable of adjusting volume control during a secondary operation mode without the need to access a plurality of volume controls, sort through software to adjust the volumes of the audio sources, or open the portable computer case to visualize volume controls for the audio sources on the main display screen.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of co-pending U.S. patentapplication Ser. No. 09/569,859, filed May 12, 2000, which is acontinuation of U.S. patent application Ser. No. 08/879,876, filed Jun.20, 1997, now U.S. Pat. No. 6,073,187, which are incorporated herein intheir entirety by reference.

[0002] This application is also related to the following co-pending,commonly owned United States Patent Application which is herebyincorporated by reference:

[0003] U.S. patent application Ser. No. 08/846,641, filed on Apr. 30,1997, issued as U.S. Pat. No. 6,006,285 on Dec. 21, 1999, entitled“COMPUTER SYSTEM CAPABLE OF PLAYING AUDIO CDS IN A CD-ROM DRIVEINDEPENDENT OF AN OPERATING SYSTEM,” to William E. Jacobs, Daniel V.Forlenza, James L. Mondshine, Tim L. Zhang, Gregory B. Memo, Kevin R.Frost, and Lonnie J. Pope.

BACKGROUND OF THE INVENTION

[0004] Description of the Related Art

[0005] Operating a CD-ROM drive in a computer system has requiredbooting an operating system and loading and utilizing a CD-ROM driveapplication. The RAM-based CD-ROM device driver of the CD-ROM driveapplication allowed for operation of the CD-ROM drive. The lengthyduration of the booting process for an operating system and theconsiderable user interaction required by a CD-ROM drive applicationrender playing an audio CD in the CD-ROM drive of a computer system, asopposed to in a conventional audio CD player, undesirable. An audio CDplayer, unlike a CD-ROM drive of a computer system, does not involve atimely initialization process and substantial user interaction. As such,despite the CD-ROM drive present in conventional computer systems, usershave maintained a separate audio CD player in place of the portablecomputer. In addition, where a user is away from his or her audio CDplayer, a conventional computer system due to its initialization anduser interaction requirements is unsuited to playing an audio CD asquickly and easily as allowed by a conventional audio CD player. Becauseof the initialization process and user interaction required, portablecomputer users would often carry a separate audio CD player for musiclistening even though the portable computer had music playingcapability. Also, since a CD-ROM drive application was dependent upon anoperating system, it was necessary to use a display screen to visuallyindicate to the user when a CD-ROM drive application was being operated.As such, portable computer users have been required to maintain theportable computer case containing a portable computer in its open stateto determine the status of a CD-ROM drive application.

[0006] Further, a conventional computer system has required a user toaccess numerous locations, software and hardware, to adjust the volumeand other settings of various audio sources such as a CD, wave, andsynthesizer for music listening. These locations typically include amixer in a Windows CD-ROM drive application for controlling the volumeof audio sources, a software master volume control in a Windows taskbar, and a hardware volume thumbwheel. As these volume control sourcescontrolled volume independent of each other, it was necessary for a userto sort through cumbersome CD-ROM drive software to adjust the volume ofthe appropriate audio sources. In light of the software nature ofcertain volume controls, it was also necessary to maintain the portablecomputer case in its open state with the display screen visible to auser to allow for certain volume adjustments during music listening.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] A better understanding of the present invention can be obtainedwhen the following detailed description of the preferred embodiment isconsidered in conjunction with the following drawings, in which:

[0008]FIG. 1 is a schematic diagram of a portable computer systemshowing an audio CD mode ROM, audio CD mode switch, status indicator,and master volume control buttons of the present invention;

[0009]FIG. 2 is a diagram of the firmware code in the audio CD mode ROMof FIG. 1 for the keyboard controller embodiment of the presentinvention;

[0010]FIG. 3 is a flow chart of the software initialization process forconfiguring the computer system of FIG. 1 for its master volume controlbuttons;

[0011]FIG. 4 is an isometric view of a portable computer case containingthe computer system of FIG. 1 in an open state;

[0012]FIG. 5 is an isometric view of the portable computer case of FIG.4 in a closed state;

[0013]FIG. 6 is an enlarged plan view illustrating the portion of thetop surface of the bottom shell of the portable computer case of FIG. 4circled and having the numeral “6” designating same, showing in moredetail the status indicator, master volume control buttons, and audio CDmode switch;

[0014]FIG. 7 is a state diagram of the power control states of thecomputer system of FIG. 1; and

[0015]FIG. 8 is a schematic electrical circuit diagram of the ministatus display screen control circuitry of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] Turning to FIG. 1, a schematic diagram of a portable computersystem S of the present invention is shown. Within the portable computerS, a CPU 10 and a Level 2 (L2) cache 12 are connected. The processor 10is preferably a Pentium® processor manufactured by Intel Corporation ofSanta Clara, Calif. The processor 10 operates preferably with a standardIBM-PC compatible operating system, such as Windows 95, available fromMicrosoft Corporation of Redmond, Wash. The L2 cache 12 providesadditional caching capabilities to the processor's on-chip cache toimprove performance.

[0017] The CPU 10 and the L2 cache 12 are connected to a host/PCI bridge14. Also connected to the host/PCI bridge 14 is a synchronous DRAM 16.The host/PCI bridge 14 is further coupled to a PCI bus P that connectsto a PCMCLA/CardBus controller 18 and a video card 20 including a videographics controller and video memory. The video graphics controller ofcard 20 provides control signals to the main liquid crystal displayscreen 406 (FIGS. 1 and 4). The PCMCIA/CardBus controller 18 is alsocoupled to a set of PCMCIA cards 22 (FIG. 1) for connecting a variety ofperipherals to the portable computer S.

[0018] A PCI/ISA bridge 24 is used to connect the PCI bus P and an ISAbus I. Coupled to the PCI/ISA bridge 24 is an IDE interface 26 whichconnects to a CD-ROM drive 28 having an IDE controller and to a harddisk drive 30. The IDE interface 26 is preferably a busmaster and anIDE/ATA interface having enhanced IDE features. The CD-ROM drive 28 ispreferably compliant with ATAPI (AT Attachment Packet Interface), theIDE standard for CD-ROM drives, and includes a CD-ROM drive controller102 that is preferably embedded in the CD-ROM drive 28. Also, integratedin the PCI/ISA bridge 24 is a set of programmable interrupt controllers(PIC) 15 for managing hardware interrupts according to their priority.The controller set 15 preferably includes two cascaded PICs for allowinginterrupt channels IRQO/-IRQ15.

[0019] Numerous chips which are preferably integrated into the PCI/ISAbridge 24 are coupled to the ISA bus I. Both a modem 32 and an audio orsound chip 34 are coupled to the ISA bus I. The sound chip 34 is furthercoupled to an acoustic output device 36 for outputting analog signalssuch as a set of speakers of the computer system S or an external stereosystem. The speakers 36 are preferably audible externally while theportable computer case S is in a closed state. In addition, the soundboard 34 is coupled to the digital master volume control buttons 35 ofthe present invention. Also, a S-IO chip 38 is coupled to the ISA bus I.The S-IO chip 38 provides a parallel port 40, a serial port 42 andconnects to a floppy disk drive 44. To more clearly illustrate thefeatures and operation of the present invention, certain otherconventional computer devices and systems not directly involved in thepresent invention are not shown.

[0020] A keyboard controller 46 is also coupled to the ISA bus I. Thekeyboard controller 46 typically connects to a keyboard 48 (FIGS. 1 and3), a PS/2 port 50, a battery 52, a port 54 coupled to the mini LCDcontrol circuitry 810 of the present invention (FIG. 8) for providingcontrol signals to a mini LCD screen 55 of the present invention and apower switch PWR_SW 58.

[0021] The keyboard controller 46 of the present invention includessystem management interrupt (SMI) circuitry for generating systemmanagement interrupts. Certain processors, such as the Pentium®processor, have included a mode referred to as a system management mode(SMM) which is entered upon receipt of a system management interrupt. ASMI is the software interrupt with the highest priority and is operatingsystem independent. Generation of a SMI also causes a SMI handler, whichis typically located in a protected memory address space of the systemDRAM 16, to be executed. A SMI handler is an interrupt service routinefor performing specific system management tasks, like reducing power tospecific devices or providing security services. SMI handler code thusmay be written by one of ordinary skill in the art to perform a varietyof system management tasks.

[0022] For the keyboard controller embodiment of the present invention,the keyboard controller 46 is further coupled to an audio CD mode switchDM_SW 56 (FIGS. 1 and 4) and the audio CD select signal DMSEL. For theCD-ROM drive controller embodiment of the present invention, the CD-ROMdrive controller 102 is coupled to the audio CD mode switch DM_SW 56 andthe audio CD select signal DMSEL. If the power switch PWR_SW 58 of thecomputer system S is in an “on” state, the audio CD mode switch DM_SW 56is disabled such that toggling of audio CD mode switch DM_SW 56 has noeffect. The audio CD mode switch DM_SW 56 is also disabled when thecomputer system S in a sleep mode. If the power switch PWR_SW 58 of thecomputer system S is in an “off” state such as a hibernate mode, theaudio CD mode switch DM_SW 56 is enabled.

[0023] When the audio CD mode switch DM_SW 56 is enabled, the state ofthe switch 56 determines whether the computer system S is in an audio CDmode. The audio CD mode switch DM_SW 56 when placed in an “on” stateserves to place the computer system S of the present invention in anaudio CD mode. Audio CD mode is a secondary operational mode whichenables the computer system S of the present invention to bypasstraditional system BIOS and play audio CDs in a CD-ROM drive 28 withoutrunning an operating system. For further details, reference is made toU.S. Pat. No. 6,006,285, entitled “COMPUTER SYSTEM CAPABLE OF PLAYINGAUDIO CDS IN A CD-ROM DRIVE INDEPENDENT OF AN OPERATING SYSTEM”incorporated above. Also, a status indicator 57 of the present inventionfor indicating when the computer system S is in an audio CD mode iscoupled to the audio CD mode switch DM_SW 56.

[0024] When the power switch 58 of a contemporary computer system isplaced in an “on” state or the power switch PWR_SW 58 of the computersystem S of the present invention is placed in an “on” state while theaudio CD mode switch DM_SW 56 is in an “off” state such that thecomputer system S is in a PC or primary operational mode, the operatingsystem of the computer proceeds to access and execute the system BIOS inthe BIOS ROM. Executing system BIOS code results in a lengthy bootingprocess wherein a power-on-self-test (POST) is performed on the systemhardware in the computer system. In order to operate a CD-ROM drive in aconventional computer, an operating system must be loaded and a CD-ROMdrive application initiated such that the device driver of the CD-ROMdrive application serves as the interface between the CD-ROM drive andthe operating system. The initiation of a CD-ROM application requiressignificant user interaction such as popping up windows and clicking onvarious portions of a computer screen.

[0025] Contrastingly, the computer system S of the present invention iscapable of avoiding the lengthy boot process associated withcontemporary BIOS ROM and the significant user interaction associatedwith a contemporary CD-ROM drive application by providing an audio CDmode. For the keyboard controller embodiment of the present invention,when the computer system S enters an audio CD mode, the processor-memorysubsystem 103, the PCI/ISA bridge 24, the CD-ROM drive 28, the host/PCIbridge 14, the audio CD mode ROM 60, and the keyboard controller 46 arepowered. ROM-based code including code for processing CD buttonselections is then loaded from an alternate ROM device, the audio CDmode ROM 60, instead of a conventional BIOS ROM device 62. An operatingsystem is not loaded, thereby significantly reducing the duration of thesystem initialization.

[0026] Rather than using a ROM device for conventional BIOS code and aseparate ROM device for the audio CD code of the present invention, thepresent invention may also be achieved by using a single ROM device. Thesingle ROM device includes a memory address range for conventional BIOScode and a memory address range for audio CD code 200 of the presentinvention. If the audio CD select signal DMSEL is unasserted, a memoryaddress range for conventional BIOS code is selected. If the audio CDselect signal DMSEL is asserted, a memory address range for audio CDcode 200 of the present invention is selected. Preferably, theconventional BIOS code and the audio CD code 200 share common code suchas POST code. Also, the firmware in the audio CD mode ROM 60 region ispreferably shadowed in the system DRAM 16 to accelerate BIOS accesses.

[0027] For the CD-ROM drive controller embodiment of the presentinvention, when the computer system S enters an audio CD mode, theCD-ROM drive 28 and the CD-ROM drive controller 102 are powered. Whilecode is loaded from an alternate ROM region for the keyboard controllerembodiment, the CD-ROM drive controller embodiment does not requireembedded code in an alternate ROM region to process CD buttonselections. Rather, a CD-ROM drive controller 102 may directly provideCD button selections to a CD-ROM drive 28. Although use of a ROM regionis described for both embodiments, the present invention extends toother non-volatile memory types.

[0028] Further, when the keyboard controller embodiment of the computersystem S is placed in an audio CD mode, an audio CD select signal DMSELis asserted and directed to a multiplexer OR gate 64. The multiplexer ORgate 64 receiving the audio CD select signal DMSEL is coupled to orintegrated into the PCI/ISA bridge 24. If the audio CD select signalDMSEL is unasserted, the multiplexer 64 selects the contemporary BIOSROM 62 by asserting a BIOS control signal, BIOS_CS. If the audio CDselect signal DMSEL is asserted, the multiplexer64 selects the audio CDmode ROM 60 of the present invention by asserting an audio CD controlsignal, DM_CS.

[0029] Referring to FIG. 2, a diagram of the audio CD firmware code 200in the audio CD mode ROM 60 is shown. The firmware 200 includes amini-version of a power-on-self-test termed quick POST 202, a miniCD-ROM device driver 208, a SMI-keyboard controller interface 206, andCD INIT 204, the initialization code for the mini CD-ROM device driver208. While a conventional CD-ROM device driver in CD-ROM applications isRAM-based, the mini CD-ROM device driver 208 in the audio CD mode ROM 60is based on a nonvolatile memory such as read-only-memory (ROM). Also,while the CD-ROM device driver in a conventional CD-ROM application mustallow for playing of audio and data CDs, the mini CD-ROM device driver208 in the audio CD mode ROM 60 allows for playing audio CDs, not dataCDs, thereby requiring less code and reducing the execution time for thedevice driver code. If a non-audio CD is present in the CD-ROM drive 28,the audio CD code opens the door of the drive 28 and generates a beep tosignal to the user that a non-audio CD is present in the drive 28.

[0030] In an audio CD mode, a CD button selection is fetched by akeyboard controller 46 in a keyboard controller embodiment of thepresent invention. A CD button selection generates an SMI therebyexecuting the SMI handler code. The SMI-keyboard controller interfacefirmware 206 is used to pass control from the keyboard controller 46 tothe SMI handler. The SMI handler places a keycode which is preferably abezel button variable corresponding to the selected CD button in amemory area termed a keycode cache. The keycode cache is preferablylocated in an extended BIOS data area segment of the SDRAM 16. The SMIhandler is also used to generate a non-maskable interrupt (NMI) whichcalls the mini CD-ROM device driver 208.

[0031] In the present invention, a NMI indicates that a bezel buttoncache corresponding to a selected CD button is ready to be fetched bythe mini CD-ROM device driver 208. The mini CD-ROM device driver 208,which is preferably a bezel button driver, fetches the bezel buttonvariable from the keycode cache. The mini CD-ROM device driver 208 thentransmits a CD packet command corresponding to the bezel button variableto the CD-ROM drive 28. The CD packet command is preferably a simplifiedversion of the Small Computer System Interface (SCSI) command and isused with an ATAPI packet command protocol. The drive 28 then issues aninterrupt request (IRQ) which informs the processor 10 that the drive 28is ready for execution of the CD packet command. Lastly, the CPU 10executes the CD packet command. The quick POST firmware 202 performs thenecessary initialization for the audio CD mode of the computer system S.For instance, the quick POST firmware 202 may test for shadow ROM areas,initialize configuration registers, power on the CD-ROM drive 28, poweroff the hard disk drive 30, power down the PCMCIA CardBus controller 18,and initialize the audio chip 34.

[0032] A conventional computer system has required a user to accessnumerous locations, software and hardware, to adjust the volumes ofvarious audio sources such as a CD, wave, and synthesizer for musiclistening. These locations typically include a mixer in a Windows CD-ROMdrive application for controlling the volume of audio sources, asoftware master volume control in a Windows task bar, and a hardwarevolume thumbwheel. As these volume control sources controlled volumeindependent of each other, it was necessary for a user to sort throughcumbersome CD-ROM drive software to adjust the volume of the appropriateaudio sources. In light of the software nature of certain volumecontrols, it was also necessary to maintain the portable computer casein an open state with the display screen visible to a user to allow forcertain volume adjustments during music listening.

[0033] The present invention eliminates these problems by providingmaster volume control buttons 35 allowing for a single source of volumecontrol which is accessible while the portable computer case C is in aclosed state. The master volume control buttons 35 are digital and arepreferably connected directly to the audio chip 34. The volume up buttonand the volume down button of the master volume control buttons 35 arehardwired inputs to the audio chip 34.

[0034] Referring to FIG. 3, a flow chart of the software initializationprocess for configuring the computer system S for the master volumecontrol buttons 35 of the present invention is shown. At step 300, thesoftware initialization process is initiated by the quick POST firmware202 when the computer system S is being placed in an audio CD mode.Next, control proceeds to step 302 wherein the audio sources controlledby the CD mixer are set to maximum volume. In this way, the full audiorange is made available for use by the digital volume control buttons 35when the computer system S is in an audio CD mode. Next, in step 304,the master volume control buttons 35 of the present invention areinitialized. In the preferred embodiment, the initialization setting forthe master volume control buttons 35 is typically about one half, or50%, of the maximum volume level. From step 304, the softwareinitialization process concludes at step 306. Thus, the software imagefor the audio CD mode is set by the quick POST firmware 202 during thesystem initialization for the audio CD mode of the present invention.

[0035] Referring to FIG. 4, an isometric view of the portable computercase C which contains the computer system S in an open state is shown.Since a conventional CD-ROM drive application was dependent upon anoperating system, it was necessary to use a conventional display screento visually indicate to a user when a CD-ROM drive application was beingoperated. As such, portable computer users have been required tomaintain a portable computer case containing a portable computer in anopen state to indicate the status of a conventional CD-ROM driveapplication to the user.

[0036] In contrast, with the present invention, whether the portablecomputer case C is maintained in a closed state or open state, a user iscapable of determining when a computer system S is in a secondaryoperational mode, such as a mode for playing audio CDs in a CD-ROM driveindependent of an operating system. The portable computer case Cincludes a top shell 404 housing a main display screen 406 along withother components and a bottom shell 408 housing a keyboard 48 along withother components. The portable computer S of the present inventionincludes a status indicator 57 for indicating when the computer system Sis in a secondary operational mode. The status indicator 57 (FIGS. 4-6)is provided on the top surface 410 of the bottom shell 408 of theportable computer case C. In the preferred embodiment, the statusindicator 57 is provided near the rear side edge 412 of the bottom shell408 at a location near the bottom or rear side edge 414 of the top shell404. The location of the status indicator 57 and other control switchesand indicators on bottom shell 408 is preferably at or near an area 409where the bottom shell 408 and top shell 404 are pivotally connected toeach other to open and close the case C. The edge 414 of top shell 404is recessed or removed at a central portion 405 in the area 407 topermit viewing of the status indicator 57 whether the case C is open(FIG. 4) or closed (FIG. 5). Also, the status indicator 57 is preferablyprovided on an upwardly angled or ramp portion 400 of the top surface410 so that the status indicator 57 may be easily seen by a user. Itshould be understood, however, that other locations on the bottom shell408 which provide convenient viewing for a user may be used.

[0037] For a computer system S capable of playing audio CDs in a CD-ROMdrive 28 independent of an operating system, the status indicator 57 ispreferably a musical note above a circle having a dot in the center ofthe circle or other appropriate icon. The status indicator 57 isprovided to the user on a mini status display screen 55 preferably of aliquid crystal composition. When the computer system S is in an audio CDmode, a pixel pattern corresponding to the icon is displayed on thestatus display screen 55. When the computer system S is in a primaryoperational mode, the icon is not displayed on the status display screen55. Thus, an icon serves as a visual cue to the user. It should beunderstood that the status indicator 57 alternatively may include oneicon for indicating a secondary operational mode and a different iconfor indicating a primary operational mode. An enlarged view of a portionof the top surface 410 of bottom shell 408 of the portable computer caseC is shown in FIG. 6. Thus, it can be seen that the status displayscreen 55 displaying the status indicator 57 is visible to the userwhether the computer case C is open (FIG. 4) or closed (FIG. 5).

[0038] The master volume control buttons 35 (FIGS. 1, 4, 5, and 6) ofthe present invention also are preferably located on the top surface 410of the bottom shell 408 of the portable computer case C at or near thelocations described above for the status indicator 57. In this way, auser is capable of adjusting volume control with buttons 35 during asecondary operational mode. This can be done without the need to openthe portable computer case C to visualize on the main display screen 406the CD mixer volume controls for the audio sources. Along with thestatus indicator 57 and master volume control buttons 35 of the presentinvention, other CD control buttons such as play/pause 420, stop 422,previous track 424, and next track 426 are similarly located on the topsurface 410 of the bottom shell 408 of the portable computer case C.

[0039] The status indicator 57 and master volume control buttons 35 dueto their location (FIGS. 4, 5, and 6) are visible when the portablecomputer case C is closed (FIG. 5) as well as open (FIG. 4). The audioCD mode control switch DM_SW 56 is also provided on the top surface 410of the bottom shell 408 such that the audio CD mode control switch DM_SW56 is accessible to the user when the computer case C is in an openstate or a closed state.

[0040] Referring to FIG. 7, a state diagram of the power control statesof the portable computer system S is shown. The power control states arecontrolled by the keyboard controller 46 for the keyboard controllerembodiment of the present invention. The S1 state is the normal “on”power state of the computer system. The S1 state corresponds to thepower control switch PWR_SW 58 having a logical state of “1.” In the S1state, the audio CD mode control switch DM_SW 56 for the secondaryoperational mode computer system is disabled such that toggling theswitch DM_SW 56 has no effect. However, in the S2 state, the audio CDmode control switch DM_SW 56 is enabled. When the power switch PWR_SW 58is switched to a “0” logical state corresponding to an “off” powerstate, the system is placed in the S2 power control state. An example ofa power control mode corresponding to the S2 power control state is ahibernate mode of the computer system S.

[0041] In the S2 state, when the audio CD mode control switch DM_SW 56is switched to a “1” logical state, the computer system S is placed inthe S3 power control state. The S3 power control state corresponds tothe normal power state for a secondary operational mode of a computersystem S such as a mode for playing audio CDs in a CD-ROM driveindependent of an operating system. In the S3 power state, the processor10 clock performs at full speed.

[0042] After power up of a secondary operation mode of the computersystem S, the audio CD code places the computer system S in the S5 powerstate using logic in the PCI-ISA bridge 24. The audio CD code alsoplaces the computer system S in the S5 power state after a CD buttonselection is processed. However, when a CD bezel button is beingprocessed, the audio CD code places the computer system S in the S3power control state. The S5 power state is a power-on-suspend (POS) modein which the processor 10 clock is stopped.

[0043] While the computer system S is in an audio CD mode, the system Sis in either the S3 power state or the S5 power state. From the S3state, toggling the audio CD mode control switch DM_SW 56 to a logicalstate of “0” returns the computer system to the S2 state. Also, from theS3 state, toggling the power control switch PWR_SW 58 to a logical stateof “1” places the computer system S in the S1 state. From the S1 state,the computer system S may also be placed in an S4 state such as thesleep mode of the computer system S. In the sleep mode of the computersystem S, the audio CD mode control switch DM_SW 56 is disabled.

[0044] Referring to FIG. 8, a schematic diagram of the mini statusdisplay screen control circuitry 810 of the present invention is shown.The control circuitry 810 is coupled between the keyboard controller 46and the mini status display screen 55. The keyboard controller 46 iscoupled to the audio CD mode switch DM_SW 56 so that the keyboardcontroller 46 may detect the status of the audio CD mode switch DM_SW56. Based on the status of the audio CD mode switch DM_SW 56, thekeyboard controller 46 provides, a plurality of control signals to themini status display screen 55.

[0045] In particular, the keyboard controller 46 generates a data signal806 and a clock signal 808 that are communicated to the data inputs oftwo shift registers 800 and 802 which are preferably serial-in,parallel-out shift registers. With each cycle or tick of the clocksignal 808, the shift registers 800 and 802 either load the data signal806 or shift the current data in the register. One of the output statesignals 812 of shift register 800 is provided as an input to shiftregister 802. The other output state signals 814 of the shift registers800 and 802 are provided to the mini status display screen 55 through anLCD connector 804 to generate activation signals for segments of themini status display screen 55. By using the keyboard controller 86 togenerate a data signal 806 and a clock signal 808, only two pins fromthe keyboard controller 46 need to be dedicated to the operation of themini status display screen 55. A plurality of the segments correspond tothe portion of the mini status display screen 55 for displaying thesecondary operational mode status indicator 57. Other segments may beused for displaying other status indicators such as a battery gaugeindicator. Preferably, each of the output state lines 814 of the shiftregisters 800 and 802 to be provided to the mini status display screen55 are intermittently illuminated. This may be done by leaving thestatus lines 814 modulated with a 60 Hz clock 816, preferably by usingexclusive-OR gates to prevent damage to the mini status display screen55. Also, an inverted clock signal 60 Hz clock 818 is used to modulatethe outputs of the LCD connector 804.

[0046] Thus, a user is capable of viewing a status indicator 57 andaccessing master volume control buttons 35 and a control switch 56 for asecondary operational mode when the portable computer case C is ineither its open state or its closed state. A user, therefore, is notrequired to maintain the case in an open state to determine whether thecomputer system S is in a secondary operational mode, to place thecomputer system S in a secondary operational mode, or to adjust mastervolume control during a secondary operational mode of the computersystem S.

[0047] The foregoing disclosure and description of the invention areillustrative and explanatory thereof, and various changes in the size,shape, materials, components, circuit elements, wiring connections andcontacts, as well as in the details of the illustrated circuitry andconstruction and method of operation may be made without departing fromthe spirit of the invention.

We claim:
 1. A method of controlling display of a status icon for anaudio CD play mode of a computer system, comprising the steps of:detecting if a computer system is in an audio CD play mode; andcontrolling display of an audio CD play status icon during the audio CDplay mode.
 2. The method of claim 1, the controlling step comprising thestep of: providing a signal to a status display screen to display theaudio CD play status icon during the audio CD play mode.
 3. The methodof claim 1, wherein the status display screen is a secondary displayscreen of the computer system.
 4. The method of claim 1, wherein thecomputer system is not fully powered during the audio CD play mode. 5.The method of claim 1, wherein the audio CD play status icon comprises amusical note icon.
 6. The method of claim 1, wherein the audio CD playmode is a secondary operational mode of the computer system.
 7. Anapparatus for controlling display of a status icon for an audio CD playmode of a computer system, comprising: a means for detecting if acomputer system is in an audio CD play mode; and a means for controllingdisplay of an audio CD play status icon during the audio CD play mode.8. The apparatus of claim 7, wherein the computer system is not fullypowered during the audio CD play mode.
 9. The apparatus of claim 7,wherein the audio CD play status icon comprises a musical note icon. 10.The apparatus of claim 7, wherein the audio CD play mode is a secondaryoperational mode of the computer system.
 11. A method of controllingvolume of a CD-ROM drive of a computer system during an audio CD playmode of the computer system, the method comprising the steps of:detecting if the computer system is in the audio CD play mode; andproviding digital volume control of the CD-ROM drive during the audio CDplay mode.
 12. The method of claim 11, the providing step comprising thestep of: providing a volume control signal to an audio controller duringthe audio CD play mode.
 13. The method of claim 11, wherein the computersystem is not fully powered during the audio CD play mode.
 14. Themethod of claim 11, wherein the audio CD play mode is a secondaryoperational mode of the computer system.
 15. An apparatus forcontrolling volume of a CD-ROM drive of a computer system during anaudio CD play mode of the computer system, the apparatus comprising: ameans for detecting if the computer system is in the audio CD play mode;and a means for providing digital volume control of the CD-ROM driveduring the audio CD play mode.
 16. The apparatus of claim 15, whereinthe computer system is not fully powered during the audio CD play mode.17. The apparatus of claim 15, wherein the audio CD play mode is asecondary operational mode of the computer system.